1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) device, and more particularly, to a substrate for an LCD device and a fabricating method thereof.
2. Discussion of the Related Art
Until recently, display devices typically employed cathode-ray tubes (CRTs). Now, flat panel displays are being used instead of CRTs. Many efforts are being made to study and develop various types of flat panel displays, such as liquid crystal display (LCD) devices, plasma display panels (PDPs), field emission displays, and electro-luminescence displays (ELDs) as substitutes for CRTs. Of these flat panel displays, the LCD devices have advantages, such as high resolution, light weight, thin profile, compact size, and low voltage power supply requirements.
In general, an LCD device includes two substrates that face each other and spaced apart with a liquid crystal material interposed between the two substrates. Each of the two substrates include electrodes that face each other. A voltage supplied to the electrodes induces an electric field across the liquid crystal material. Alignment of the liquid crystal molecules in the liquid crystal material changes in accordance with the intensity of the induced electric field into direction of the induced electric field, thereby changing the light transmissivity of the LCD device. Thus, the LCD device displays images by varying the intensity of the induced electric field.
FIG. 1 is a perspective view of an LCD device according to the related art. As shown in FIG. 1, an LCD device 11 includes an upper substrate 5, a lower substrate 22, and a liquid crystal material 14 between the substrates. The upper substrate 5 is referred to as a color filter substrate that includes a color filter pattern 8, a black matrix 6 between the color filter patterns 8, a common electrode 18 on both the color filter pattern 8 and the black matrix 6. The lower substrate 22 is referred to as an array substrate that includes a pixel electrode 17, a thin film transistor T, a gate line 13, a data line 15, and a storage capacitor C. The data line 15 and the gate line 13 cross each other to define the pixel region P. Each pixel region P includes a pixel electrode 17 and a thin film transistor T, which is used as a switching device. The thin film transistor T is disposed adjacent to where the gate line 13 and the data line 15 cross. The storage capacitor C is connected to the pixel electrode 17 and has a storage electrode 30 as a first electrode and uses the gate line 13 overlapping the storage electrode 30 as a second electrode. There is a possibility of light leaks in the LCD device due to a misalignment in the attachment of the upper and lower substrates 5 and 22.
FIG. 2 is a cross-sectional view taken along line II-II of FIG. 1. As shown in FIG. 2, a thin film transistor T includes a gate electrode 32, a semiconductor pattern 34, a source electrode 36 and a drain electrode 38 disposed on the first substrate 22. A passivation layer 40 is disposed on the thin film transistor T. A black matrix 6 corresponding to a gate line 13, a data line 15 and a thin film transistor T is disposed on the second substrate 5. Red, green and blue color filter patterns 8a, 8b and 8c corresponding to respective pixel regions P are also disposed on the second substrate 5.
To prevent cross-talk, the data line 15 and the gate line 13 are space apart from the pixel electrode 17 by a first distance A and a second distance B, respectively. Since light leakage can happens through the first and second distances A and B, the black matrix 6 covers the first and second distances A and B. Further, the black matrix 6 blocks incident light from affecting the semiconductor pattern 34. Due to the possibility of misalignment during attachment of the upper and lower substrates 5 and 22, the black matrix 6 has a margin of error to compensate for the misalignment. Thus, an aperture ratio of the LCD is reduced. When misalignment during attachment of the upper and lower substrates 5 and 22 is more than the margin of error, some of the first and second distances A and B are not covered by the black matrix 6 so that light leakage occurs. Therefore, display quality of the LCD is reduced.